Radial flow reactors are widely used to contact fluid reactants that are typically vapor with particulate catalyst. Radial flow reactors typically include a cylindrical vessel with a main inlet duct (inlet distributor) at one end and an annular chamber or series of chambers (scallops) arranged annularly around the interior periphery of the vessel for distributing reactants to an annular catalyst bed disposed inwardly of the scallops. A central outlet pipe (center-pipe) is disposed inwardly of the annular catalyst bed and is connected to a reactor outlet for the exit of product from the reactor. The scallops and the outlet center-pipe are permeable to fluid flow but impermeable to catalyst flow to contain the catalyst bed therebetween.
Examples of processes carried out in such an apparatus include various hydroprocessing techniques such as catalytic reforming, hydrotreating, dehydrogenation, dehydrocyclodimerization and isomerization. Additionally, radial flow reactors can be used in continuous-catalyst-regeneration reactor systems.
As mentioned above, a known type of radial reactor includes a series of scallops arranged concentrically around an outer periphery of the bed of catalyst. Each scallop is open at the top to allow vapor from the reactor head space to travel down the scallop. The top (open end) of the scallop typically protrudes above a cover deck that prevents downward vapor flow through the top section of the catalyst bed. The desired flow pattern is an equal amount of vapor going down each scallop arranged around the periphery of the reactor vessel. The vapor would then flow out of the scallops, through the catalyst and into the center-pipe. The scallops are formed by connecting multiple scallop members together into one long scallop chamber. A radially-inward face of each scallop is constructed of a screen or perforated plate to permit fluid flow from the scallop radially inwardly to the bed of catalyst. A center-pipe is constructed of a plurality of parallel wires or screen mesh covering a perforated pipe so as to permit the passage of vapor and prevent individual catalyst particles from passing through the screen.
However, these conventional scallops and center-pipes may cause or fail to correct the non-uniform distribution of vapor through the catalyst. A properly designed reactor inlet distributor is required to direct vapor toward the scallops within the headspace of the radial flow reactor. The non-uniform distribution of vapor could have detrimental effects on the reactor performance through the non-uniform utilization of catalyst and large variation in the force exerted by the vapor on the coverdeck or other internals. The non-uniform distribution of vapor in the reactor can negatively impact the yield of products from the reactor and reduce the efficiency or yield of the reactor; therefore, a need exists for a modified reactor inlet distributor to cause the flow to be more uniformly distributed within the head space of the reactor. Reactor inlet distributors can be made from materials commercially available; however, the specific design of these inlet distributors has a significant impact on the flow of vapors within the reactors head space.